Method and means for introducing vibrato effects into sound



Aug. 21, 1951 H. M LEONARD METHOD AND MEANS FOR INTRODUCING VIBRATO EFFECTS INTO SOUND Filed Sept. 21, 1945 2 Sheets-Sheet 1 INVENTOR Harry M. Leonard ATTORNEY Aug. 21, 1951 H. M. LEONARD 2,565,033

METHOD AND MEANS FOR INTRODUCING VIBRATO EFFECTS INTO SOUND Filed Sept. 21, 1945 2 Sheets-Sheet 2 INVENT OR Harn M. Leonard BY %zw/ ATTO RN EY Patented Aug. 21, 1951 METHOD AND MEANS FOR INTRODUCING VIBRATO EFFECTS INTO SOUND Harry Mills Leonard, Los Angeles, Calif.

Application September 21, 1945, Serial No. 617,783 5 Claims. (01. 179 -1003) This invention relates to a method and means for introducing a vibrato effect into sound during the reproduction thereof.

The invention to be described hereinafter refers to copending application Serial Number 617,782, filed Sept. 21, 1945, entitled Method and Means for Introducing Vibrato and/or Echo Effects into Sound, and has been developed for use in motion picture work, but it will become obvious to those skilled in the art that the same method and the same means could be readily adapted for use in radio work, and in fact in all places where a vibrato effect is desirable in reproduced sound.

In reproducing sound, particularly singing and certain musical instruments, it has been found desirable to introduce into the tone a vibrato effect to enhance the value of the music. The vibrato effect referred to, sometimes termed a tremulo effect, is already known and has been used by singers and musicians for some time to improve the quality of their music. In the motion picture industry and in the radio broadcast field it has been found desirable to use a vibrato effect not only in music but also in speech to give to the voice of a speaker different qualities such as the characteristics of an aged person.

In its preferred form my invention provides a method and a means for inexpensively and controllably introducing a vibrato effect into sound either during recording, as set forth in the above mentioned application, or during reproduction as set forth herein. The method Was conceived particularly to meet the requirements of the motion picture art wherein it is necessary to have precise control of the frequency and the amplitude of the vibrato introduced. The means is a simple, inexpensive addition to the already established apparatus for reproducing sound. The object, therefore, of this invention is to provide a simple, inexpensive method and means for introducing vibrato effects into sound which is capable of being regulated to control the characteristics of the vibrato effects being introduced.

Other objects and advantages will become apparent as the description proceeds in conjunction with the drawings in which:

Figure 1 is a perspective diagrammatic view showing the arrangement of electrically operated parts used for practicing my invention;

Figure 2 is a diagrammatic view showing the parts of Figure 1, with the addition of other parts commonly used in reproducing sound;

Figure 3 is a diagrammatic view showing an arrangement of parts mechanically operated for practicing my invention; and

Figure 4 is an arrangement of parts showing still another way for introducing vibrato effects into reproduced sound under my invention.

Briefly stated, the method in my invention amounts to introducing a vibrato effect into reproduced sound in one of two ways. First, either by oscillating a scanning beam over a uniformly traveling sound track; or, secondly by holding the scanning beam stationary and moving the track past the scanning beam with a cyclically varying speed.

Referring to the drawings for a description of the means used for practicing my invention, it will be seen in Figures 1 and 2 that I have diagrammatically illustrated a form of an electrically operated apparatus used for this purpose. In this form of my invention, I use an oscillating mirror to vibrate the scanning slit of light over a uniformly moving sound track. In these views, ll designates a light source which customarily is a specially formed filament adapted to emit a line of light. In conjunction with this light source, I use a condenser lens 12 which condenses the light from source ll onto a slit M in a mask 13. The slit M passes a flat beam or slit of light L, which in ordinary practice is focused upon a sound track 15 one. uniformly moving film F by means of an optical system IS. The light passing through the sound track impinges upon a photoelectric cell I! which produces fluctuating electric currents in accordance with the pulsations of light passing through the film. The above described arrangement is an ordinary conventional set-up for reproducing sound.

In my invention I use all the elements above described but introduce another element into the apparatus; namely, a galvanometer mirror l8 which intercepts the beam of light L from the optical system l6 before it impinges upon the film F. This mirror as shown is set to slightly defiect the light beam when in normal position. The galvanometer is connected to conductors I9 and 20 which lead to an oscillator 2|, the oscillator 2| being subject to frequency control by the knob 22 and amplitude control by the knob 23.

In practice I introduce vibrato effects into sound by vibrating the mirror l8 through the oscillator 2|. The mirror I8, when oscillating, vibrates the beam of light up and down the track l-5 as shown by the dotted lines 24 in Figure 2. It will be observed that the vibration of the beam of light over the sound track is above and below the normal position of the beam. The movement of the beam up and down over the track,

while the track is moving uniformly in the direction of the arrow 25, will introduce a variation of the true frequencies above and below the normal frequencies on the track and will thus produce a vibrato effect in the output of the system. This variation, as before stated, may be controlled both with respect to the periodic frequency and the amplitude, and is sometimes referred to as an eighth, a quarter, or a half tone variation. In practice, a satisfactory frequency is in the neighborhood of four to six cycles per second. The amplitude of course will depend upon the effects desired. The output of the system may be sent to a regular electrical channel for recording in any known manner or it may be sent directly to a speaker system for reproduction.

In Figures 3 and 4, I have shown other forms Which my invention may take. These forms are distinct from that shown in Figures 1 and 2 in that the means for introducing the vibrato effect is mechanically controlled instead of electrically controlled. Referring to Figure 3, it will be seen that this arrangement has the same elements as shown in Figures 1 and 2. However, in this form I oscillate the mirror l8 by mechanical means instead of electrical means. For this purpose the mirror I8 is mounted for rotation upon an axis 26 and is adapted to be rotated on its axis by a depending arm 21. Upon the arm 21, I mount a sleeve 28 which is adjustably slidable along the arm to control the amount of oscillation of the mirror. Pivotally connected to the slidable member 23 is a rod 29 which is mounted upon an eccentric 30 driven by a motor MI. The rod 29 may be telescopically connected to the eccentric 30 for extensible purposes of adjustment, which may be fixed at any point by the thumb nut 31.

In addition to the above described eifects and means for producing the same, I may introduce another effect which will tend to enhance the vibrato effect introduced by oscillating the scanning beam. This effect deals with a periodical variation of the amplitude of the output signal synchronized with the periodical variation of the frequency. For this purpose I use an ordinary potentiometer generally designated P which is placed across the output of the photo-electric cell [1. The potentiometer used in this case is knob controlled; that is, the moving parts are mounted upon a central shaft 3| and the shaft 3| in turn is rotated by 2. depending arm 32. Mounted upon the arm 32 is an adjustably slidable sleeve 33 and pivotally connected to the sleeve 33 is a rod 34. For purposes of adjustment, the rod 34 in turn may be telescopically connected to a larger rod 35 which works upon an eccentric 36 driven by a motor M2. If the motor M2 runs in synchronism with the motor MI and the oscillation of the mirror l8 and the potentiometer P are properly phased, the result will be a variation of the frequency output of the signal and a variation in the amp itude of the output signal which are combined and synchronized to produce a'pleasing vibrato effect either in music or in voice. To get this combined effect, the motors MI and M2 ore electrically interlocked and may be driven by any well known master control, such as a Selsyn system, which keeps the motors in step. Since such. srstcm is well known in the art. no description of it will be entered here, it being deemed sufficient to show that the motors MI and M2 are interlocked by conductors 31 and 38 respectively,

leading to the same master control.

Another mechanical form which my invention may take consists of means for periodically varying the speed of the film as it passes a stationary scanning slit of light. This form is shown in Figure 4. Here it will be noted are the same elements as shown in Figure l, 2, and 3, with the difference that the oscillating mirror i8 is not shown in this view. The same light source and the same optical system is used to produce an identical scanning beam of light. In this case the light beam impinges directly upon the film E which is moved over a shoe 39 that contains the photo-electric cell [1. In ordinary practice, the film is moved over the shoe by a feed sprocket 40 which is customarily driven at uniform speed. In my invention I change the sprocket 40 from a uniformly driven sprocket into an eccentrically mounted sprocket which when driven by a shaft 4| will generate an uneven travel of the film F over the shoe 39. This uneven travel of the film will develop into a cyclically varying speed which will depend upon the rotation of the sprocket 40 for its frequency. The result is a periodic variation of the normal frequencies above and below the instantaneous mean value, which is sometimes referred to as an eighth, a quarter, or a half tone variation. In a conventional machine, the rotation of the sprocket 40 is in the order of four times per second, which produces a frequency variation of the same order. However, this frequency may be varied by changing the diameter of the sprocket with a corresponding change in the speed of the film and the amplitude variation may be controlled through the eccentricity of the sprocket 43.

The forms of my invention shown hereinbefore cover both an electrically operated and a mechanically operated means for introducing vibrato into reproduced sound. The electrically operated equipment lends itself particularly well to control in that the frequency and the amplitude of the variation may be controlled during the act of reproduction, whereas in the mechanical means any control must be effected by mechanical adjustments. However, all the physical forms which my invention may take fall within the scope of the method described and claimed.

I claim:

1. A method for introducing vibrato into sound produced by scanning a sound track with a light beam consisting in causing a periodic variation in the pitch of said sound by cyclically varying the speedwith which said beam scans said track and periodically attenuating the volume of said sound in synchronism with the periodic variation of said pitch.

2. In a sound reproducing machine having means for moving a sound track relative to a light scanning beam, a mirror arranged to intercept said beam and means for oscillating said mirror to vibrate said beam in the direction of movement of said track.

3. In a sound reproducing machine having means for moving a sound track past a light scanning beam,- a mirror arranged to intercept said beam, a motor for oscillating said mirror to periodically vary the normal frequency of said sound, a potentiometer for attenuating the volume of said sound, a motor for controlling said potentiometer to periodically attenuate said sound, and means for interlocking said first mentioned motor with said last mentioned motor to synchronize the frequency variation of said sound with the amplitude variation thereof.

4. A method for introducing vibrato into sound produced by uniformly moving a sound track past a. light scanning beam consisting in oscillating said light scanning beam in the direction of movement of said track and varying the volume of sound produced thereby in synchronism with the oscillation of said light scanning beam.

5. In a sound reproducing machine having means for moving a sound track relative to a light scanning beam a mirror arranged to intercept said beam, means for oscillating said mirror to vibrate said beam in the direction of movement of said track, attenuation means for periodically varying the volume of sound reproduced by said machine and means for actuating said attenuation means in synchronism with the oscillation of Said mirror.

HARRY MILLS LEONARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,024,609 Smythe Dec. 17, 1935 2,075,861 Mueller Apr. 6, 1937 2,113,400 Dimmick Apr. 5, 1938 2,165,777 Batsel July 11, 1939 2,245,354 Mroz June 10, 1941 2,322,884 Roetken Jan. 29, 1943 2,347,084 Cooney Apr. 18, 1944 2,373,560 Hanert Apr. 10, 1945 2,402,095 Slyfield June 11, 1946 FOREIGN PATENTS Number Country Date 605,132 France Feb. 13, 1926 

